The subject matter disclosed herein relates to a secondary disconnect mechanism for a circuit breaker. In particular, the subject matter disclosed herein relates to a secondary disconnect that provides a secondary source of electrical power to accessories in the racked-in and test positions of a circuit breaker drawout system.
Drawout circuit breakers often include a mechanism for moving the breaker in and connecting the breaker to corresponding electrical contacts, a location known as the “racked-in” position. When in the racked-in position, the circuit breaker is coupled to the main electrical circuit and provides the interruption functionality for which it is intended. If the drawout mechanism is reversed to the “racked-out” position, the circuit breaker is disconnected from the electrical contacts and the main electrical circuit. The circuit breaker may be moved to the racked-out position, for example, when maintenance is performed on the main electrical circuit. Typical racking mechanisms often include a third or test position. In the test position the circuit breaker can be closed, opened or tripped in order to check internal and external accessories such as auxiliary switches, shunt trip and under voltage and secondary circuits.
To test the accessories, electrical power is provided to the accessories to enable proper functioning. The electrical power is typically provided from a secondary source, such as a disconnectable mechanism that includes slidable electrical contacts. However, these disconnectable mechanisms typically require a large amount of physical space in which to operate. As smaller circuit breakers, such as molded case circuit breakers for example, are used with drawout mechanisms, it is increasingly difficult to fit the slidable mechanism within the available space.
While existing secondary disconnects for drawout mechanisms are suitable for their intended purposes, there still remains a need for improvements particularly regarding secondary disconnecting mechanisms that provide a reliable and cost effective means for providing electrical power to circuit breaker accessories when in the racked-in and test positions.